When tilling the soil, the use of tilling implements with flexible teeth or rigid teeth mounted on spring-loaded articulations is known.
In the implements known as cultivators, used for loosening the soil, this flexibility is put to use to achieve better loosening using the vibrations of the teeth, but also for freeing the teeth by elastic retraction when they encounter obstacles such as pebbles, stones, branches, etc.
British Patent GB-A-1,025,413 describes a tooth of this type comprising:
a flexible e-shaped element whose upper end is attached to a cross member of the tilling implement by means of clamps, PA1 a bent arm whose upper part is connected with the end of the flexible element by a U-shaped body whose interior has a recess for receiving this part, PA1 and a tooth attached to the free end of the arm. PA1 in the area where they are attached to the implement, by a lower plate with an L-shaped cross section pressing the curved ends of the blades against the lower forward angle of a cross member under the clamping effect of clamps, PA1 and in the vicinity of the arm of the tool: PA1 by a tightening plate inserted between the two legs of the body, PA1 by tenons projecting from one of the two elements, body or plate, and engaging holes provided at least in the side blades, PA1 and by mounting bolts traversing the tightening plate, the center blade, the arm of the tool, and the interior of the body.
In practice, the flexibility of the teeth allows them to retract backward describing, in a vertical plane, a release path that gradually raises the active part above the obstacle, then, once the obstacle is past, to return by elasticity to their initial working position. In very stony soil, the teeth more frequently encounter obstacles which, by reason of the only release option being upward, tend to raise them too often, thus altering the quality of work.
Another drawback of this type of tooth is that, under the influence of the vibrations and bending of the blades, their means of removable attachment to the tilling implement and to the tools eventually becomes loose, leading to loss or breakage of elements and hence to lost time.